Yukon Cornelius Posted June 29, 2020 Share Posted June 29, 2020 My son's barn find 86 Brat. Has multiple issues we've been working through. Currently were working on the charging system. The alternator is charging at 14v at idle but the charge warning light burn dim. EGR, brake, charge, and stop lamp. These light go out at near 2k RPM. I'm pulling the alternator out now to check the brushes. Any ideas fellas? Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 29, 2020 Share Posted June 29, 2020 Alternator has failed. GD 1 Link to comment Share on other sites More sharing options...
DaveT Posted June 29, 2020 Share Posted June 29, 2020 Every time I have seen this it was one of the alternator brushes. 1 Link to comment Share on other sites More sharing options...
Ionstorm66 Posted June 29, 2020 Share Posted June 29, 2020 (edited) Check with a meter in AC voltage at the alternator. Should be under 1V, very close to zero. If it as a external regulator, check at the regular instead. Forget what year that went to integrated regulators. Edited June 29, 2020 by Ionstorm66 Link to comment Share on other sites More sharing options...
Yukon Cornelius Posted June 29, 2020 Author Share Posted June 29, 2020 Link to comment Share on other sites More sharing options...
Yukon Cornelius Posted June 29, 2020 Author Share Posted June 29, 2020 Testing with AC now. .07 VAC Link to comment Share on other sites More sharing options...
Ionstorm66 Posted June 29, 2020 Share Posted June 29, 2020 Next would be bad ground somewhere. Simple test is to stick a jumper cable from battery negative to the alternator, and one from alternator to chassis. Link to comment Share on other sites More sharing options...
Yukon Cornelius Posted June 29, 2020 Author Share Posted June 29, 2020 Contacts looked ok. Diodes were kinda corroded. Cleaning contacts and retesting. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted June 29, 2020 Share Posted June 29, 2020 The battery indicator shows if the voltage potential is higher at the battery OR the alternator. So a poor connection, bad alt, or bad battery could do it. Generally though if the light goes out at higher rpm it's the alt. May have just been light corrosion on the slip rings that will wear off as it runs. GD Link to comment Share on other sites More sharing options...
Yukon Cornelius Posted June 29, 2020 Author Share Posted June 29, 2020 Meh, cleaned the contacts and reassembled. Still does the same thing. Not one of the more pressing issues with the vehicle as its charging 14v during operation. And the list of issues is long. I'll come back to it and report a repair when I find it. It's most likely just diode issues. But, not bad enough to fail the diode test on my tester. Moving on to rear brake hardware and fuel level sensor Link to comment Share on other sites More sharing options...
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